Update requirements.txt

[ahuang11]

Summary

Since it pins x86_64, users see the error in #28

If we just let users install it, they can fix it by following the resulting error:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/andrew/mambaforge/envs/ray_38/lib/python3.8/site-packages/ray/__init__.py", line 100, in <module>
    _configure_system()
  File "/Users/andrew/mambaforge/envs/ray_38/lib/python3.8/site-packages/ray/__init__.py", line 44, in _configure_system
    raise ImportError(
ImportError: Failed to import grpc on Apple Silicon. On Apple Silicon machines, try `pip uninstall grpcio; conda install grpcio`. Check out https://docs.ray.io/en/master/ray-overview/installation.html#m1-mac-apple-silicon-support for more details.

Sneaked in example updates to match prefect-dask

Relevant Issue(s)

Checklist

• Summarized PR's changes in CHANGELOG.md